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i have sometimes used the word "smooth" to describe the image quality of the 7x42 Ultravid plus. I used to think it was an inadequate word, but after reading this article it makes some sense now and explains what I see (high resolution).

I think I understand what you mean.
Once, I compared my Trinovid non-HD with an Opticron Natura BGA, both in 8x42.
I always had the perception of the Opticron being a little bit sharper and like you say, the Leica somewhat ‘smoother’, and that thereby it had a better resolution..
But when looking at a black electricity cable in front of the sky, the Leica showed more detail of the moss etc. hanging on it. I could really see that difference when holding them steady
I thought it was remarkable because I didn’t expected that:).

I just picked up an original Swaro CL 8x30. I used to have one (purchased back in 2013) and I loved it to bits.
It was my second favorite bino (ultravid 7x is #1) of all owned. I sold it back in 2015 I think as I just started
wearing glasses and had a very difficult time adjusting to the CL with glasses. Well, I always missed it and saw the new ones out and the original (1st gen) CL's becoming harder to find. I grabbed one (same color as before - sand/tan) for a good price around same time I purchased FL just recently. It actually won my heart again and I decided to swap out the FL with it even though FL has better optics. That's the short version of that story.

Anyway, I was always perplexed by reports on the forum about the first CL being not sharp enough for some users.
I used to think what the heck do these guys see? I'm seeing enough detail. I still see the same nice and satisfying image with my second CL just acquired. It's clear to me that it's not as sharp as ultravid or FL . However I'm seeing good detail and it's quite bright. I would characterize the CL view as gentler than my ultravid, not as razor sharp or "biting" with contrast. Well now I'm realizing the CL has high resolution but edge contrast/sharpness not as high. It has a pleasant and smooth view to it with good contrast and colors, but I wouldn't characterize it as razor sharp. I'm seeing good detail ... quite good actuality and overall the original CL, to me, has a very good image. Only gripe is true FOV could be wider.

This article helps me to have a better understanding of aspects of image quality in my binoculars.

Maybe this stuff was clear to everyone else, but sharpness/resolution difference was never fully understood by me.

I think I understand what you mean.
Once, I compared my Trinovid non-HD with an Opticron Natura BGA, both in 8x42.
I always had the perception of the Opticron being a little bit sharper and like you say, the Leica somewhat ‘smoother’, and that thereby it had a better resolution..
But when looking at a black electricity cable in front of the sky, the Leica showed more detail of the moss etc. hanging on it. I could really see that difference when holding them steady
I thought it was remarkable because I didn’t expected that:).

Grtz

exactly. I took the CL (original version, not the latest) to the park yesterday and saw excellent detail of an old bird nest. A song sparrow was inspecting it and flew out of it. Plenty of detail but perhaps not biting sharp like my ultravid which seems to have both high resolution and high edge contrast making the image appear very sharp too.

You are quite right that the distinction between resolution and sharpness is often muddled on the forum, but as you discovered they are important distinct features of a binocular design. While analysis of both are often featured in promotional material and reviews of cameras and/or lenses there is virtually nothing available for binoculars. The excuse has been (the totally erroneous presumption) that the eye is invariably limiting. As that link shows, the distinction between resolution and sharpness is quite easily illustrated in a photographic print, but is often somewhat less obvious in binocular usage, but It's something that is clearly important for customer choice. I've been shown analysis curves by both Zeiss and Meopta, but neither would allow it to be made public.

I suspect you might recall that I wasn't at all keen on the original Swarovski CL, but would agree that both the FL and Ultravid HD plus are significantly better. I'd put the difference down to both resolution and sharpness. I suspect the current Trinovid HD is even weaker on sharpness.

From what I've read so far about the Trinovid hd it's supposedly super sharp on axis.
Perhaps people are conflating the two terms again, I don't know and I haven't looked through
one yet.

Yes, I do remember the not so great impressions you had of the original CL. It seemed polarizing with one camp
liking it and others feeling it was underwhelming especially for Swarovski. I can't find the post, but I recall a year or 2 ago Chuck (Chill) finally getting his hands on one and expecting it to be rubbish based on past forum posts, but instead he was pleasantly surprised and liked it. I think expectations were quite high when it was first introduced.
I never had an issue with it except I'd like to see a wider FOV. Sweet spot at least is huge and I realize that's due to fuzzy edges being cut out of the field. But still it's nice to see most of the whole field in good focus.

I think It's comparable to a good Asian mid-priced roof (500 bucks) with a betterl build/construction and aesthetic design, perhaps a little brighter in the 30/32mm size with great ergonomic feel in the hand. It should have retailed around 800 bucks instead of around 1200 when it first came out and dealers could have sold it for about 700 new. Sales and used units could have been had for 500-600. I think at lower pricing it may have gained more acceptance in the forum...perhaps. The Swarovski name and made in Austria made the retail price higher. I got this second one for 780 bucks new in box and it's a 2015 production model. I'm happy with it. It's for light carry, casual bird watching while the 7x42 is always the primary bino.

Glad you found what you were looking for on an 8x30/32. I went to the MT Cuba center then to Ashland in Delaware yesterday, a bit cold, but a nice enough day with my EII 8X30. I have never viewed the 8X30 CL, previous or late model, I am sure it is better built than the stuff coming from the east these days.

Glad you found what you were looking for on an 8x30/32. I went to the MT Cuba center then to Ashland in Delaware yesterday, a bit cold, but a nice enough day with my EII 8X30. I have never viewed the 8X30 CL, previous or late model, I am sure it is better built than the stuff coming from the east these days.

Andy W.

Thanks Andy. I owned a Nikon SE 8x32 several years back for some months.
I remember it being truly razor sharp; optics clearly on a higher level than original CL. Never tried EII but know from here that it's special.

I just picked up an original Swaro CL 8x30. I used to have one (purchased back in 2013) and I loved it to bits.
It was my second favorite bino (ultravid 7x is #1) of all owned. I sold it back in 2015 I think as I just started
wearing glasses and had a very difficult time adjusting to the CL with glasses. Well, I always missed it and saw the new ones out and the original (1st gen) CL's becoming harder to find. I grabbed one (same color as before - sand/tan) for a good price around same time I purchased FL just recently. It actually won my heart again and I decided to swap out the FL with it even though FL has better optics. That's the short version of that story.

Anyway, I was always perplexed by reports on the forum about the first CL being not sharp enough for some users.
I used to think what the heck do these guys see? I'm seeing enough detail. I still see the same nice and satisfying image with my second CL just acquired. It's clear to me that it's not as sharp as ultravid or FL . However I'm seeing good detail and it's quite bright. I would characterize the CL view as gentler than my ultravid, not as razor sharp or "biting" with contrast. Well now I'm realizing the CL has high resolution but edge contrast/sharpness not as high. It has a pleasant and smooth view to it with good contrast and colors, but I wouldn't characterize it as razor sharp. I'm seeing good detail ... quite good actuality and overall the original CL, to me, has a very good image. Only gripe is true FOV could be wider.

This article helps me to have a better understanding of aspects of image quality in my binoculars.

Maybe this stuff was clear to everyone else, but sharpness/resolution difference was never fully understood by me.

Hi Beth

Sounds like you've been bitten by the bug again!

You must really like the little CL if it has booted the 8×32FL out of a home! ...... good to see you with a nice lightweight option though, and handbag sized too :) - hope you enjoy !

You must really like the little CL if it has booted the 8×32FL out of a home! ...... good to see you with a nice lightweight option though, and handbag sized too :) - hope you enjoy !

Chosun

Thanks CJ ! The CL has better ergonomics and is about 2 ounces or so lighter.
It's less bulky and slightly more portable as a result. FL is fantastic though and the optics are obviously better. But, as I said, the CL optics are certainly good enough to enjoy and quite bright for 8x30. One small surprise is that it works as well as FL with my glasses. The eyecups of both bins are almost flush with the ocular lenses and I think this helps. I've saved a little money too and that aligns with my other goal of saving for retirement. FL sold quickly for about the same price I got it for but ebay fees put me behind. So only around a few hundred bucks savings from FL to CL but savings is savings.

Just came back from optometrist and have pupils dialated. My mom had glaucoma so they have to check me each time for this and other issues.
Have slight cataracts :(

I don't think the article is analogous to binoculars. The article describes the merits of having more pixels and how that "smooths" the image. And while this is accurate, the human/binocular equation is purely analog. No pixels.

I do think that resolution and (perceived) sharpness can be somewhat different things. Higher contrast can often affect how sharp an image will appear and also aid focusing. But the higher contrast optics may not perform better on a resolution chart, carefully viewed with a rest, for example.

I recently encountered this while comparing Nikon 8x30 MHGs to Zeiss 8x25 Victorys.
The Victorys seemed to focus a little faster as the point of sharpness was slightly more apparent. However, when viewing a USAF chart and other texts from a steady rest, the Monarchs ultimately resolved as well as the Victorys.

For both camera lenses and binoculars the manufacturers use the same method of analysing contrast vs. spatial frequency. It's known as the modular transfer function (MTF) and yields both the optical resolution and a contrast values for the angular frequency for optimal sharpness. This would typically be 5 to 10 arcminute AFoV for binoculars. The analysis can be further refined by analysing multiple wavelengths. We have been able to ascertain a certain amount of data regarding resolution and effective resolution of the final products, but so far, very little at all relating to sharpness. That's currently something we have to compare for ourselves.

It's not so different. At least theoretically we have the visual receptor packing density as the comparable physical limit for detector resolution, but relatively few of us can approach the Nyquist limit for visual acuity.

i have sometimes used the word "smooth" to describe the image quality of the 7x42 Ultravid plus. I used to think it was an inadequate word, but after reading this article it makes some sense now and explains what I see (high resolution).

Hi GG,

I'm not sure that I agree with this fellow, largely because of his definitions. The best distinction I've seen is within the definition of acutance, where

Quote:

...Acutance is related to the amplitude of the derivative of brightness with respect to space. Due to the nature of the human visual system, an image with higher acutance appears sharper even though an increase in acutance does not increase real resolution.

Got that?

Anyway, there might be the equivalent to 'acutance' in binocular images projected directly onto the retina, but I have no idea about how to go about measuring it or how it corresponds with the observer's perception of "sharpness."

Ed

__________________Understanding optics is child's play compared to understanding child's play. "Science is the belief in the ignorance of the experts." Richard Feynman

It wouldn't be wrong to use the term acutance with regard to binoculars. However, in practice I it seems the word is so closely associated with the artificial enhancement of edge sharpness in photographic image processing that I think it mostly serves to mislead here.

The scientific literature on this subject is rather complex and I've struggled to get the clear cut answers I was looking for. At the risk of over simplifying the story, our perception of sharpness is believed to be to do with how fast our brains process different levels of visual information. The accumulation and interpretation of the signals from the retina for the detail at the limit of acuity is slow, and can take half a second or so. You will need to stop and concentrate. That is too slow for many everyday tasks. Just imagine trying to catch a ball if your visual frame rate was 2 frames a second. In fact, most of the time the brain processes information, not at the 20/10 to 20/20 acuity level of detail, but at 20/50 to 20/100 level and a speed of around 50 frames per second. It allows us to spot and track fast moving objects, like a thrown ball and respond accordinly. Our perception of sharpness is apparently to do with the level of contrast at the 20/50 to 20/100 level of detail.

In birding terms, the low definition contrast, or sharpness, dictates how readily we can spot that little movement that gives away a bird's position, and high resolution provides us with the finest detail to make a challenging ID.

The optical designers are able to manipulate the levels of resolution and sharpness for application and commercial reasons. It would seem from comments comments that individuals weight the importance of these two properties rather differently and make purchase choices accordingly, even if they struggle to give the properties the correct name. ;-)

It wouldn't be wrong to use the term acutance with regard to binoculars. However, in practice I it seems the word is so closely associated with the artificial enhancement of edge sharpness in photographic image processing that I think it mostly serves to mislead here.

The scientific literature on this subject is rather complex and I've struggled to get the clear cut answers I was looking for. At the risk of over simplifying the story, our perception of sharpness is believed to be to do with how fast our brains process different levels of visual information. The accumulation and interpretation of the signals from the retina for the detail at the limit of acuity is slow, and can take half a second or so. You will need to stop and concentrate. That is too slow for many everyday tasks. Just imagine trying to catch a ball if your visual frame rate was 2 frames a second. In fact, most of the time the brain processes information, not at the 20/10 to 20/20 acuity level of detail, but at 20/50 to 20/100 level and a speed of around 50 frames per second. It allows us to spot and track fast moving objects, like a thrown ball and respond accordinly. Our perception of sharpness is apparently to do with the level of contrast at the 20/50 to 20/100 level of detail.

In birding terms, the low definition contrast, or sharpness, dictates how readily we can spot that little movement that gives away a bird's position, and high resolution provides us with the finest detail to make a challenging ID.

The optical designers are able to manipulate the levels of resolution and sharpness for application and commercial reasons. It would seem from comments comments that individuals weight the importance of these two properties rather differently and make purchase choices accordingly, even if they struggle to give the properties the correct name. ;-)

David

David,

Although I'm not steeped in the visual motion detection literature, what you're saying doesn't correspond with my general understanding as reflected in the attached not-so-recent articles. I'd be very interested to read an article showing that "...our perception of sharpness is believed to [do] with how fast our brains process different levels of visual information."

I haven't time to read those articles fully just nwo but at a glance I'm really not sure they are addressing the same issues? The explanation I offered was distilled from reading countless abstracts from mostly relatively recent publications, but I understand the pioneering studies were done by Zeiss some time ago. Unfortunately I've not seen the original publication (which I think were in German) but I'll see what I can dig out later.

Isn't acutance essentially apparent sharpness? I'm familiar with the term from reading about optics online, but I always interpreted it as apparent sharpness. When we use the term 'edge contrast' when referring to binocular images I think of edge contrast relating directly to apparent sharpness. Is it not enhanced edge contrast that can render an image sharp when viewed through a binocular ? I may be conflating all these terms, but think when attempting to describe quality of images through binoculars edge contrast would be the approx or appropriate term to gauge or evaluate perceived sharpness which is subjective form user to user. The original article I posted illustrates a difference between sharpness created by edge contrast (how I understand it) to be different from resolution. Edge contrast i understand to mean the boundaries between two tones (lighter/darker) to be distinct making the tones easier to differentiate.
So in everyday language, when referring to images from cameras or binoculars, the general term "sharpness" is used in place of more specific terms like acutance.
I may be getting all this wrong. When responding please remember I'm not a scientist and to "dumb" it down a bit if you don't mind

How many bird watchers actually achieve the sharpness or resolution that one can get in tests of tripod mounted binoculars?

I cannot judge, as I am not an experienced bird watcher, and critically I don't have much accommodation.

In my viewing of general terrestrial subjects with hand held standard binoculars, I find that, firstly, critical focus is not achieved with moving objects.
This is illustrated by the Minolta Autofocus 8x23 binocular in good daylight. It locks on to a moving person's face with great precision, better than I can achieve with any other hand held binocular, although Canon IS binoculars are maybe better, as they deal with hand movement, but not with focus.

This hand movement, in my experience, drastically reduces the resolution or sharpness.
Things may appear to be sharp, but they aren't.
I have frequently experienced resolution with the Canon IS binoculars at least double of that with a normal hand held binocular. Unseen detail is immediately seen, when not even hinted at with a standard binocular.

I remember following an unknown distant aircraft with the Canon 8x25 IS. When I engaged the stabiliser, not only could I read the name ETIHAD, but I saw the letters were yellow. They are actually gold coloured. None of this detail was seen without the stabiliser. I don't think I even realised there was a name on the fuselage side.

With movement with unaided eyes, this is detected way off axis, even though the resolution of the eyes at this position must be very poor.

When following fast moving birds you rarely can acquire perfect focus, so you must rely on a general impression and this is where good ID skills come in.

This is why I like lower powered binoculars b/c you get a slightly less shaky image. You can't look for warblers with a tripod obviously but you could do this for ducks and geese in fields; static type of birding. When IS bins are improved enough to the point where they work great with glasses, are lighter and better ergonomically and have super long battery life I would consider buying one.

Isn't acutance essentially apparent sharpness? I'm familiar with the term from reading about optics online, but I always interpreted it as apparent sharpness. When we use the term 'edge contrast' when referring to binocular images I think of edge contrast relating directly to apparent sharpness. Is it not enhanced edge contrast that can render an image sharp when viewed through a binocular ? I may be conflating all these terms, but think when attempting to describe quality of images through binoculars edge contrast would be the approx or appropriate term to gauge or evaluate perceived sharpness which is subjective form user to user. The original article I posted illustrates a difference between sharpness created by edge contrast (how I understand it) to be different from resolution. Edge contrast i understand to mean the boundaries between two tones (lighter/darker) to be distinct making the tones easier to differentiate.
So in everyday language, when referring to images from cameras or binoculars, the general term "sharpness" is used in place of more specific terms like acutance.
I may be getting all this wrong. When responding please remember I'm not a scientist and to "dumb" it down a bit if you don't mind

Hi GG,

No need to dumb anything down. The way I'd put it is that sharpness is the perceptual response to acutance, which is a measurable property of the image. But, as the quote in #15 states, increased acutance (resulting in increased sharpness) isn't necessarily accompanied by increased resolution. Edge contrast is a good descriptor for acutance so we're in perfect agreement.

Thanks,
Ed

__________________Understanding optics is child's play compared to understanding child's play. "Science is the belief in the ignorance of the experts." Richard Feynman

No need to dumb anything down. The way I'd put it is that sharpness is the perceptual response to acutance, which is a measurable property of the image. But, as the quote in #15 states, increased acutance (resulting in increased sharpness) isn't necessarily accompanied by increased resolution. Edge contrast is a good descriptor for acutance so we're in perfect agreement.

Although I'm not steeped in the visual motion detection literature, what you're saying doesn't correspond with my general understanding as reflected in the attached not-so-recent articles. I'd be very interested to read an article showing that "...our perception of sharpness is believed to [do] with how fast our brains process different levels of visual information."

Thanks,
Ed

Ed,

I’ve now had a more detailed look at those two papers. They exploring the computational models for the popular theories of movement detection. Although I mention ball catching, that wasn’t the issue I was addressing. I know motion is rather more complex. The publications ignore the contrast and spatial frequency parameters. However the Borst and Englehaaf paper does draw attention to the need for temporal gating (which I called frame rate) as a prerequisite for movement detection and velocity determination, as it is for scenario I pieced together.

As I mentioned earlier I my understanding was built up in fragments gleaned from weeks of browsing to build up a relevant interpretation. Unfortunately that was about 4 years ago, and I’m struggling to relocate some pieces in the puzzle now. Particularly the older work that identified the contrast of the 5 to 10 arcminute frequency range as most critical for sharpness perception. I’ll let you know when I find it.

While I was trying to track down those missing pieces, I found a paper I hadn’t seen before that I thought might interest you. In it’s introduction, it looks like it cites some of the studies I looked at before, which mostly used black and white targets. It goes on to investigate aspects of spatial and temporal frequency, in addition to contrast on vision sensitivity using more natural visual information. It covers a lot but doesn’t paint the complete picture. I’m still struggling on some parts of the paper, but haven’t found anything yet that appears to contradict the main thrust of what I said. However it does shift things around quite a bit. I need to go through it again to figure out the implications. https://www.ncbi.nlm.nih.gov/pmc/art...7/#!po=41.4894